ON-CHIP IMAGE-PROCESSING ALGORITHM FOR REAL-TIME CCD-BASED STAR TRACKERS AND WAVE-FRONT SENSORS

In this paper, we describe on-chip and off-chip image-processing algorithms utilizing the internal architecture of recently developed CCD sensors to provide high-speed readout of selected portions of the imager or accelerated scanning of an entire CCD frame. Image-processing time comparable to the star-tracker sensor exposure time and to the characteristic time of the atmospheric fluctuations (10 ms) has been achieved. On-chip image processing is particularly suitable for space or ground-based real-time applications (position determination, tip-tilt correctors, wavefront sensing for adaptive optics systems) where the speed of acquisition and processing data from the ''regions of interest'' is critical. An example of a star tracker (based on the Texas Instruments TC217 CCD image sensor) for space applications capable of providing real-time multiple position updates with high angular resolution is given and achieved performance is discussed.